There are many situations in which it is important to be able to accurately detect particles above a predetermined size in a gas stream since a gas utilization device downstream of the detector will be damaged if encountered by a gas stream with particles. One particularly illustrative example of this is a gas turbine which utilizes hot combustion gases in order to do the mechanical work, generate electricity, or the like.
Gas turbines are particularly sensitive to particles in the hot combustion gas stream. Even a small number of particles over 10 micrometers in size will quickly damage a turbine blade, which not only requires replacement of the blade, but can shut down an entire facility for a significant period of time. For that reason, a wide variety of different particle separators have been devised, such as filters, centrifugal separators, and the like, which remove the particles before they get to the turbine. If the particle separator breaks down or is damaged, however, or a sudden change in the fuel causes differences in the particle load, potentially damaging particles can move past the particle separator, which will damage the turbine.
No known systems are in existence which will reliably determine the change in the quality of the stream of gases from a combustion facility to the turbine downstream of the particle separator. Conventional particle detecting or measuring devices typically are not capable of detecting small amounts of fine particles in large flows of gas, such as exist downstream of the particle separators in the flow of hot combustion gases to a turbine. Conventional detection systems may cause false alarms, or simply inadequately determine when potentially damaging particles (e.g. with a size greater than about 10 micrometers) flow in a post-particle separator gas stream.
According to the present invention, it is possible to adequately detect--and then take appropriate corrective action--when particles larger than a predetermined size are passing in a post-particle separator stream to a gas utilization device, such as a gas turbine. This is accomplished, according to the invention, by providing a particle concentrating means disposed between the particle separator and the gas utilization device, and providing a particle detecting means associated with the particle concentrating means. In response to the particle detecting means, an activity will be initiated which prevents damage to the gas utilization device, such as activating an alarm whereby an operator takes corrective action, putting an alternative/substitute particle separator on line, shutting down the combustor, etc.
According to one aspect of the present invention, upstream of a device for using gases--such as a turbine--a particle removing means removes particles greater than a predetermined size. The particle concentrating means is disposed between the turbine and the particle remover, and a particle detector is associated with the concentrating means. An alarm, or the like, responsive to the particle detecting means initiates activity which prevents damage to the turbine when an undesirable level of particles is detected. The particle concentrating means comprises a cyclone, such as a horizontal cyclone or a flow through cyclone. The particle detecting means may be a gas trap disposed in the particle discharge from the cyclone, and a detecting chamber operatively connected to the gas trap.
According to the method of the present invention, damage to a device for utilizing gases that is easily damaged by particles of greater than a predetermined size is prevented. The method comprises the steps of essentially sequentially: (a) Effecting removal of particles greater than the predetermined size from a gas stream. (b) Concentrating any particles greater than the predetermined size remaining in the gas stream by subjecting the gas stream to cyclonic action. (c) Detecting the level of concentrated particles greater than the predetermined size; and (d) in response to step (c) initiating activities that prevent damage to the gas utilization device.
According to another aspect of the invention, an assembly for creating and using hot combustion gases is provided. The assembly comprises: Means for combusting fuel to produce hot combustion gases having particles therein. Means for removing particles greater than a predetermined size from the hot combustion gases. A conduit extending from the particle removing means. A turbine operatively connected to the conduit. A cyclone disposed in the conduit between the particles removing means and the turbine. A particle discharge from the cyclone. A particle trap disposed in the particle discharge. And, particle detecting means operatively associated with the particle trap.
It is the primary object of the present invention to provide for the effective protection of a gas turbine or like device readily damaged by particles in a gas flow. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.